Re: CSS contrast (#30295) (was Re: Heads-up: Emacs 26.1 RC1)

[Yuri Khan]

On Wed, Mar 21, 2018 at 2:56 AM, Richard Copley <address@hidden> wrote:

> Patch 1 is a small fix for the current formula using color-distance.
> Patch 2 uses luminance as in Tom's original patch.
> I think patch 2 gives better contrast.

Why not use the WCAG contrast ratio formula?

https://www.w3.org/TR/WCAG20/#visual-audio-contrast

(Except that, if implemented literally, it will probably not fit the
trivial change threshold.)